Dynamic Loading:->Routine is not loaded until it is called->Better memory-space utilization; unused routine is never loaded.->Useful when large amounts of code are needed to handle infrequently occurring cases.->No special support from the operating system is required implemented through program design.Dynamic Linking:->Linking postponed until execution time.->Small piece of code, stub, used to locate the appropriate memory-resident library routine.->Stub replaces itself with the address of the routine, and executes the routine.->Operating system needed to check if routine is in processes’ memory address.->Dynamic linking is particularly useful for libraries.Overlays:->Keep in memory only those instructions and data that are needed at any given time.->Needed when process is larger than amount of memory allocated to it.->Implemented by user, no special support needed from operating system, programming design of overlay structure is  complex.